The only vegetarians I've ever been annoyed by are the Stealth Vegetarians I used to encounter when catering for weddings. Most weddings run off a limited menu, with pre-registered orders, so the kitchen staff can get the entire meal prepped for extremely rapid deployment, and the waitstaff can run trays with the exact food for each table. Vegetarians are absolutely not a problem in this system. People who see their neighbor's vegetarian pasta and decide they'd rather have that then the pork loin they ordered three months ago are an enormous pain to deal with, particularly since these special individuals tend to cluster. Since the waitstaff load trays by table, and the cooks probably don't produce a spare vat of vegetarian food, at the very least the carefully prepped logistics get gummed up, and at the worst somebody ends up trying to make a couple extra pastas on like three minutes notice.

These days I'm almost purely vegetarian when left to my own devices. What I find continually interesting is people who happily eat meat by the bucket, but react strongly to even a vague description of slaughtering an animal. Seems to me there's a sort of fundamental dissonance there. I've slaughtered animals, it's fine. Not my favorite job, but not super-unpleasant either. I'd certainly feel very strange eating meat at all if I couldn't tolerate the deed, let alone the concept of the deed.